Robert Boyle (1627-1691)
Tracts Written by the Honourable Robert Boyle, Containing New Experiments,
Touching the Relation Between Flame and Air. And About Explosions ...
London, 1672 [from Henry Marshall Leicester and Herbert S. Klickstein,
A Source Book in Chemistry 1400-1900 (New York: McGraw Hill,
1952)]
The First Title.
Of the Difficulty of Producing Flame without Aire.
Experiment I.
A Way of Kindling Brimstone in vacuo Boyliano Unsuccessfully Tried.
We took a small earthen melting Pot, of an almost Cylindrical figure, and well
glaz'd (when it was first bak'd) by the heat; and into this we put a small
cylinder of Iron of about an inch in thickness, and half as much more in
Diameter, made red hot in the fire; and having hastily pump'd out the Air, to
prevent the breaking of the Glass; when this vessel seem'd to be well emptied,
we let down, by a turning key, a piece of Paper, wherein was put a convenient
quantity of flower of Brimstone, under which the iron had been carefully
plac'd; so that, being let down, that vehement heat did, as we expected,
presently destroy the contiguous paper; whence the included Sulphur fell
immediately upon the iron, whose upper part was a little concave, that it might
contain the flowers when melted. But all the heat of the iron, though it made
the Paper and Sulphur smoke, would not actually kindle either of them that we
could perceive.
Experiment II.
An Ineffectual Attempt to Kindle Sulphur in Our Vacuum Another
Way
Another way I thought of to examine the inflammability of Sulphur without Air;
which, though it may prove somewhat hazardous to put it in practice, I resolved
to try, and did so after the following manner:
Into a glass-buble of a convenient size, and furnish'd with a neck fit for our
purpose, we put a little flower of Brimstone (as likely to be more pure and
inflammable than common Sulphur;) and having exhausted the Glass, and secured
it against the return of the Air, we laid it upon burning coals, where it did
not take fire, but rise all to the opposite part of the glass, in the form of a
fine powder; and that part being turned downward and laid on coals, the
Brimstone, without kindling, rose again in the form of an expanded substance,
which (being removed from the fire) was, for the most part, transparent, not
unlike a yellow varnish.
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Though these unsuccessful attempts to kindle Sulphur in our exhausted
Receivers, were made more discouraging by some more, that were made another
way; yet judging that last way to be rational enough, we persisted somewhat
obstinately in our endeavours, and conjecturing that there might be some
unperceived difference between Minerals, that do all of them pass, and are sold
for common Sulphur, I made trial, according to the way hereafter to be
mentioned, with another parcel of brimstone, which differ'd not so much from
the former, as to make it worth while to set down a description o it, that
probably would not be useful.
But in this place, it may suffice to have given a general intimation of the
possibility of the thing. The proof of it you will meet with under the
third Title, when I come to tell you what use I endeavour'd to make of
our sulphureous Flames.
Experiment III.
Shewing the Efficacy of Air in the Production of Flame, without Any
Actually Flaming or Burning Body.
Having hitherto examin'd by the presence of the Air, what interest it
has in kindling of Flame; it will not be impertinent to add an Experiment or
two, that we tried to shew the same interest of the Air by the effects of its
admission into our Vacuum. For I thought, it might reasonably be
supposed that if such dispositions were introduc'd into a body, as that there
should not appear any thing wanting to turn it into Flame but the presence of
the Air, an actual ascension of that body might be produced by the admitted
Air, without the intervention of any actual Flame, or Fire, or even heated
substance; the warrentableness of which supposition may be judged by the two
following Experiments.
When we had made the Experiment, ere long to be related in its due place,
(viz. Title II. Exper. the 2nd) to examine the presumption we had, that
even when the Iron was not hot enough to keep the melted Brimstone in such a
heat, as was requisite to make it burn without Air, or with very little, it
would yet be hot enough to kindle the Sulphur, if the Air had access to it: to
examine this (I say) we made two or three several Tryals, and found by them,
that if some little while after the flame was extinguished, the Receiver were
removed, the sulphur would Presently take fire again, and flame as vigorously
as before. But I thought it might without absurdity be doubted, whether or no
the agency of the Air in the production of the flame might not be somewhat less
than these trials would perswade; because that, by taking off the Receiver, the
Sulphur was not only exposed to fresh Air, but also advantaged with a free
scope for the avolution of those fumes, which in a close Vessel might be
presum'd to have been unfriendly to the Flame.
How far this doubt may, and how far it should, be admitted, we may be assisted
to discern by the subjoined experiment, though made in great part for another
purpose; which you will perceive by the beginning of the Memorial I made of it,
that runs thus;
Experiment IV.
A Differing Experiment to the Same Purpose with the
Former.
Having a mind to try, at how great a degree of rarefaction of the Air it was
possible to make Sulphur lame by the assistance of an adventitious heat, we
caused such an experiment as the above mention'd to be reiterated, and the
pumping to be continued for some time after the flame of the melted flowers of
Brimstone appeared to be quite extinguished, and the Receiver was judged by
those that managed the Pump (and that upon probable signs) to be very well
exhausted. Then, without stirring the Receiver, we let in at the stop-cock
very warily a little Air, upon which we could perceive, though not a constant
flame, yet divers little flashes, as it were, which disclosed themselves by
their bleu [sic] colour to be sulphureous flames; and yet the Air, that had
suffic'd to re-kindle the Sulphur, was so little, that two exsuctions more drew
it out again, and quite depriv'd us of the mentioned flashes. And when a
little Air was cautiously let in again at the stop-cock, the like flashes began
again to appear, which, upon two exeuctions [sic] more did again quite vanish,
though, upon the letting in a little fresh Air the third time, they did once
more reappear.
Whether and how far such experiments as these may conduce to explicate what is
related of Fires suddenly appearing in long undisclosed Vaults or Caves to
those that first broke into them, I may perchance elsewhere consider; but shall
not here, enquire, especially being not fully satisfied of the truth of the
matter of fact. ...
The Second Title.
Of the Difficulty of Preserving Flame without Air
Since it is generally, and in most cases justly, esteemed to be more easie to
preserve Flame in a body that is already actually kindled, than to
produce it there at first; we thought fit to try, whether at least
bodies already burning might not be kept in that state without the concurrence
of Air. And though in some of our formerly published Physico-mechanical
experiments it happen'd that actually Flame would scarce last a minute or two
in our large Pneumatical Receiver; yet because it seem'd not improbable,
that mineral bodies once kindled might afford a vigorous and very durable
flame; we thought fit to devise and make the following tryals: Whence probably
we might receive some new information about the Diversities, and some
other Phenomena of Flame, and the various degrees, wherein the Air is
necessary or helpful to them.
Experiment I.
Reciting an Attempt to Preserve the Flame of Brimstone without
Air
We put upon a thick metalline place a convenient quantity of flowers of
Sulphur; and having kindled them in the Air, we nimbly conveyed them into a
Receiver, and made haste to pump out some of the included Air, partly for other
reasons, and partly that the cavity of the Receiver might be the sooner freed
from smok [sic], which would, if plentiful, both injure the flame, and hinder
our sight. As soon as the Pump began to be plied, or to be lessen'd at every
exsuction of the Air; and in effect, it expir'd before the Air was quite drawn
out. Nor did it, upon the early removal of the Receiver, do any more than
afford, for a very little while, somewhat more of the smoak in the open Air,
than it appear'd to do before.
The reiteration of this experiment presently after, afforded us nothing new,
worth mentioning in this place.
Experiment II.
Relating a Tryal about the Duration of the Flame of Sulphur in
vacuo Boyliano.
To vary a little the foregoing Experiment, and try to save some moments of
time, which on these occasions is to be husbanded with the utmost care; having
provided a Cylinder of ion larger than the former, that it might be its bulk,
being once heated, both contribute to the asccension [sic] of the Sulphur, and
to the lasting of its flame, we made a tryal, that I find registred to this
effect:
We took a pretty big lump of Brimstone, and tied it to the turning-key; and
having got what else was necessary in a readiness, we caus'd the iron-plate to
be hastily brought red-hot from the fire, and put upon a Pedestal, that the
flame might be the more conspicuous; and, having nimbly cemented on the
Receiver, we speedily let down the suspended Brimstone, till it rested upon the
red-hot iron, by which being kindled, it sent up a Pump, till we had, as we
conjectur'd, emptied the Receiver; which we could not do without withdrawing
together with the Air much sulphureous smok, (that was offensive enough both to
the eyes and nostrils.) But notwithstanding this pumping out of the Air,
though the flame did seem gradually to be somewhat impaired; yet it manifestly
continued burning much longer, than by the short duration of other flames in
out Receivers (when diligence is us'd to withdraw the air from them) one could
have expected. And especially one time, (for the experiment was made more than
once) the flame lasted, till the Receiver was judg'd to be well exhausted; and
some thought it did so survive the exhaustion, that it went not out so much for
want of Air, as Fuel; the Brimstone appearing when we took off the Receiver,
either to have been consum'd by the fire that fed on it, or to have casually
run off from the Iron, whose heat had kept it constantly melted.
In case you should have a mind to prosecute Experiments of the nature of this
and the precedent, it may not prove useless, if I intimate to you the following
Advertisements.
1. For the red-hot iron above mentioned, we thought it not amiss to provide,
instead of the melting-pot imploy'd in the first experiment, a Pedestal (if I
may so call it) made of a lump of dryed Tobacco-pipe-clay, that the vehement
heat of the iron might neither fill the Receiver with the smok of what it
lean'd on, nor injure the engine, if it should rest immediately upon that; And
this Pedestal should be so plac'd, that the iron may be as far, as you can,
from the sides of the Receiver, which else the excessive heat would endanger.
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